🤖 Merge PR DefinitelyTyped#71163 fix(styled-system): fix conditionals to make it work with exactOptionalPropertyTypes: true by @yuhr

Author: yuhr

types/styled-system/index.d.ts

@@ -37,9 +37,10 @@ export type ResponsiveValue<
     ThemeType extends Theme = RequiredTheme,
 > = T | null | Array<T | null> | { [key in ThemeValue<"breakpoints", ThemeType> & string | number]?: T };
 
-export type ThemeValue<K extends keyof ThemeType, ThemeType, TVal = any> = ThemeType[K] extends TVal[] ? number
-    : ThemeType[K] extends Record<infer E, TVal> ? E
-    : ThemeType[K] extends ObjectOrArray<infer F> ? F
+export type ThemeValue<K extends keyof ThemeType, ThemeType, TVal = any> = NonNullable<ThemeType[K]> extends TVal[]
+    ? number
+    : NonNullable<ThemeType[K]> extends Record<infer E, TVal> ? E
+    : NonNullable<ThemeType[K]> extends ObjectOrArray<infer F> ? F
     : never;
 
 export interface SpaceProps<ThemeType extends Theme = RequiredTheme, TVal = ThemeValue<"space", ThemeType>> {

types/styled-system/tsconfig.json

@@ -11,7 +11,8 @@
         "strictFunctionTypes": true,
         "types": [],
         "noEmit": true,
-        "forceConsistentCasingInFileNames": true
+        "forceConsistentCasingInFileNames": true,
+        "exactOptionalPropertyTypes": true
     },
     "files": [
         "index.d.ts",