feat(es-lint-rule) eslint no-unused-param rule more strict (#3499)

* Modifying the eslint no-unused-param rule to be a bit more strict while still allowing unused parameters for handlers.
This allows us to catch a bit more cases when the parameter truly isn't used and shouldn't be part of the function signature.

* Standardized error handling between querying via WMS or via WFS and improved the error handling in general as well for the WMS layer type in particular

Author: Alex-NRCan

.github/copilot-instructions.md

@@ -325,6 +325,24 @@ See [time-dimension.md](../docs/programming/time-dimension.md) for the full arch
 
 GeoView uses a lightweight typed delegate event system (see [event-helper.md](../docs/programming/event-helper.md)). Classes own private handler arrays (`#onXxxHandlers`) and expose `onXxx()`/`offXxx()` subscribe/unsubscribe methods. Events are emitted via `EventHelper.emitEvent()`. Controllers subscribe in `onHook()` and unsubscribe in `onUnhook()`.
 
+**Handler parameter naming convention (required):** For EventHelper delegate handlers, always name parameters `sender` and `event`.
+
+- Use `(sender, event)` even if one parameter is not used in the body.
+- `sender` and `event` are exception names in the no-unused-parameter ESLint rule.
+- Apply this convention in controllers, domains, APIs, and any callback wired to `onXxx()` EventHelper delegates.
+
+```typescript
+// ✅ Good
+mapViewer.onMapMoveEnd((sender, event) => {
+  logger.logDebug(event.lonlat);
+});
+
+// ❌ Avoid
+mapViewer.onMapMoveEnd((map, e) => {
+  logger.logDebug(e.lonlat);
+});
+```
+
 ## TypeScript Conventions
 
 ### Type Safety (Strict Enforcement)
@@ -352,6 +370,25 @@ const layers: string[] = [];
 useState<TypeBasemapProps[]>([]);
 ```
 
+- **Prefer optional property syntax for optional attributes/properties**: For class attributes and type/interface properties that may be absent, prefer `prop?: Type` over `prop?: Type | undefined`.
+
+```typescript
+// ✅ Good: concise optional property
+interface LayerConfig {
+  layerName?: string;
+}
+
+// ❌ Avoid in most cases: redundant undefined union on optional property
+interface LayerConfig {
+  layerName?: string | undefined;
+}
+
+// ✅ Exception: use this only when presence-vs-absence must be distinguished
+interface LayerState {
+  layerName: string | undefined;
+}
+```
+
 - **Avoid name collisions**: Use `GVLayer` not `Layer` when OpenLayers has a `Layer` class
 
 ### String Concatenation

docs/programming/best-practices.md

@@ -38,6 +38,27 @@ async fetchMetadata(id: string): Promise<void> {
 const handleClick = useCallback((): void => { ... }, []);
 ```
 
+Prefer optional property syntax (`?:`) for class attributes and type/interface properties that may be absent. In most cases, this is clearer than using an explicit `| undefined` union.
+
+```ts
+// Preferred in most cases
+class LayerInfo {
+  layerName?: string;
+}
+
+type TypeLayerConfig = {
+  sourceUrl?: string;
+};
+
+// Use only when presence-vs-absence must be distinguished
+class LayerState {
+  // Property is always present, but value can be undefined
+  sourceUrl: string | undefined;
+}
+```
+
+Use `property: Type | undefined` only when that distinction is intentional and required by behavior (for example: serialization differences, merge semantics, or APIs that depend on checking whether a key exists).
+
 ## 2- Avoid using variable names that are too short.
 
 It is difficult to know what a variable with the name `e` refers to. Is it an `element`, an `event` or anything else whose name starts
@@ -249,7 +270,25 @@ In classes, functions should be ordered in the following way:
 - static private
 - event types
 
-## 12- React Performance Patterns
+## 12- EventHelper handler parameter naming
+
+When subscribing to events emitted through our `EventHelper` delegates, handler methods should use the parameter names `sender` and `event`.
+
+This naming is required for consistency and readability across the codebase. These names are also treated as exceptions in our no-unused-parameter ESLint rule, so they should be used even when one of the arguments is not consumed in the implementation.
+
+```ts
+// ✅ Good: EventHelper delegate naming convention
+this.getMapViewer().onMapMoveEnd((sender, event): void => {
+  logger.logDebug('Map moved', event.lonlat);
+});
+
+// ✅ Also good when one parameter is intentionally unused
+this.getMapViewer().onMapInit((sender, event): void => {
+  initializeSomething();
+});
+```
+
+## 13- React Performance Patterns
 
 ### useMemo Naming Convention
 

packages/eslint.config.js

@@ -107,7 +107,7 @@ export default [
       'no-useless-constructor': 'off',
       '@typescript-eslint/no-useless-constructor': 'error',
       'no-unused-vars': 'off',
-      '@typescript-eslint/no-unused-vars': 'warn',
+      '@typescript-eslint/no-unused-vars': ["warn", { "args": "all", "argsIgnorePattern": "^_|^event$|^sender$" }],
       '@typescript-eslint/no-unnecessary-type-assertion': 'warn',
       '@typescript-eslint/no-inferrable-types': 'warn',
       'no-use-before-define': 'off',

packages/geoview-core/src/api/types/layer-schema-types.ts

@@ -468,7 +468,7 @@ export type RCSLayerConfig = {
   /**
    * The display name of the layer (English/French). This overrides the default name coming from the GeoCore API.
    */
-  geoviewLayerName?: string | undefined;
+  geoviewLayerName?: string;
 
   /** Initial settings to apply to the GeoCore layer at creation time. */
   initialSettings?: TypeLayerInitialSettings;
@@ -491,7 +491,7 @@ export type GeoPackageLayerConfig = {
   metadataAccessPath: string;
 
   /** The display name of the layer. This overrides the default name coming from the GeoCore API. */
-  geoviewLayerName?: string | undefined;
+  geoviewLayerName?: string;
 
   /** Initial settings to apply to the layer at creation time. */
   initialSettings?: TypeLayerInitialSettings;
@@ -514,7 +514,7 @@ export type ShapefileLayerConfig = {
   metadataAccessPath: string;
 
   /** The display name of the layer. This overrides the default name coming from the GeoCore API. */
-  geoviewLayerName?: string | undefined;
+  geoviewLayerName?: string;
 
   /** Initial settings to apply to the layer at creation time. */
   initialSettings?: TypeLayerInitialSettings;

packages/geoview-core/src/api/types/map-schema-types.ts

@@ -1049,7 +1049,7 @@ export type TypeFeatureInfoEntry = {
   uid?: string;
   feature?: Feature<Geometry>;
   geometry?: Geometry;
-  extent: Extent | undefined;
+  extent?: Extent;
   featureIcon?: string;
   fieldInfo: Partial<Record<string, TypeFieldEntry>>;
   nameField?: string;

packages/geoview-core/src/core/components/common/layer-list.tsx

@@ -35,7 +35,7 @@ export interface LayerListEntry {
   /** Number of features in the layer. */
   numOffeatures?: number;
   /** Array of feature info entries. */
-  features?: TypeFeatureInfoEntry[] | undefined;
+  features?: TypeFeatureInfoEntry[];
   /** Unique DOM id for the layer list item. */
   layerUniqueId?: string;
   /** Whether the layer item is disabled. */

packages/geoview-core/src/core/components/data-table/export-button.tsx

@@ -17,7 +17,7 @@ interface ExportButtonProps {
   layerPath: string;
   rows: DataTableRow[];
   columns: MRTColumnDef<DataTableRow>[];
-  children?: ReactElement | undefined;
+  children?: ReactElement;
 }
 
 /** The columns to remove from the data when exporting */

packages/geoview-core/src/core/components/guide/guide.tsx

@@ -68,7 +68,7 @@ export const Guide = memo(function GuidePanel({ containerType }: GuideType): JSX
    * Handles search state changes from GuideSearch component.
    */
   const handleSearchStateChange = useCallback(
-    (newSearchTerm: string, newHighlightFunction: (content: string, sectionIndex: number) => string): void => {
+    (_newSearchTerm: string, newHighlightFunction: (content: string, sectionIndex: number) => string): void => {
       setHighlightFunction(() => newHighlightFunction);
     },
     []

packages/geoview-core/src/core/components/layers/delete-undo-button.tsx

@@ -128,12 +128,10 @@ export function DeleteUndoButton(props: DeleteUndoButtonProps): JSX.Element {
     }
   };
 
-  // eslint-disable-next-line @typescript-eslint/no-unused-vars
   const handleDeleteClick = (event: MouseEvent): void => {
     performDelete(false);
   };
 
-  // eslint-disable-next-line @typescript-eslint/no-unused-vars
   const handleUndoClick = (event: MouseEvent): void => {
     performUndo(false);
   };

packages/geoview-core/src/core/components/layers/right-panel/layer-opacity-control/layer-opacity-control.tsx

@@ -74,6 +74,7 @@ export function LayerOpacityControl({ layerPath }: LayerOpacityControlProps): JS
    * @param updateStore - Should the store be updated.
    */
   const handleSliderChange = useCallback(
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
     (value: number | number[], activeThumb: number, updateStore = false): void => {
       const val = (Array.isArray(value) ? value[0] : value) / 100;
       const newValue = Math.min(val, layerParentOpacity);