Treat the isList-from-shape inference in ConstantArrayType symmetrically

The empty-keys block unconditionally overrode `$isList` from the
unsealed key type, while the non-empty path only filled it in when
null — an asymmetry. No caller actually passes a non-null `$isList`
for an empty CAT, so the override and the only-when-null path were
equivalent today, but the rule was inconsistent on its face.

Wrap both branches in `if ($isList === null)` so the constructor
consistently says "trust the caller when given, infer from shape
otherwise". Also drop the stale `makeList()` TODO — the comment
was speculating about validation that would require `isList=Maybe`
co-occurring with a non-list-compatible shape, a state that no
source-level flow actually constructs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ondrejmirtes

src/Type/Constant/ConstantArrayType.php

@@ -144,25 +144,29 @@ public function __construct(
 	{
 		assert(count($keyTypes) === count($valueTypes));
 
-		$keyTypesCount = count($this->keyTypes);
-		if ($keyTypesCount === 0) {
-			if ($unsealed === null) {
-				$isList = TrinaryLogic::createYes();
-			} else {
-				[$unsealedKeyType] = $unsealed;
-				if ($unsealedKeyType instanceof NeverType && $unsealedKeyType->isExplicit()) {
+		// Fill in `$isList` from the shape when the caller didn't pass one.
+		// For empty CATs the answer derives from the unsealed key type
+		// (no explicit keys to inspect); for non-empty ones the default
+		// is `No` and the caller is expected to assert list-ness via
+		// `makeList()` if appropriate.
+		if ($isList === null) {
+			if (count($this->keyTypes) === 0) {
+				if ($unsealed === null) {
 					$isList = TrinaryLogic::createYes();
-				} elseif ($unsealedKeyType->isInteger()->yes()) {
-					$isList = TrinaryLogic::createMaybe();
 				} else {
-					$isList = TrinaryLogic::createNo();
+					[$unsealedKeyType] = $unsealed;
+					if ($unsealedKeyType instanceof NeverType && $unsealedKeyType->isExplicit()) {
+						$isList = TrinaryLogic::createYes();
+					} elseif ($unsealedKeyType->isInteger()->yes()) {
+						$isList = TrinaryLogic::createMaybe();
+					} else {
+						$isList = TrinaryLogic::createNo();
+					}
 				}
+			} else {
+				$isList = TrinaryLogic::createNo();
 			}
 		}
-
-		if ($isList === null) {
-			$isList = TrinaryLogic::createNo();
-		}
 		$this->isList = $isList;
 
 		if ($unsealed !== null) {
@@ -3053,8 +3057,6 @@ public function makeList(): Type
 			return new NeverType();
 		}
 
-		// todo can't be a list if keyTypes are not subsequent integers, or if unsealed type is not int keys
-
 		return $this->recreate($this->keyTypes, $this->valueTypes, $this->nextAutoIndexes, $this->optionalKeys, TrinaryLogic::createYes(), $this->unsealed);
 	}