Return array explicitly for non-list fetch modes instead of falling back

When the extension returned null for FETCH_KEY_PAIR, FETCH_GROUP, and
FETCH_UNIQUE modes, the fallback in MethodCallReturnTypeHelper used a
parametersAcceptor selected from named argument variants. On PHP 8.5,
the named variants for fetchAll() have only a mode parameter and return
list<mixed>, causing incorrect list inference for non-list modes.

Fix by having the extension explicitly return array<mixed, mixed> for
non-list modes instead of returning null and relying on the fallback.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Type/Php/PdoStatementFetchAllReturnTypeExtension.php

@@ -54,26 +54,33 @@ public function getTypeFromMethodCall(
 			return null;
 		}
 
+		$isList = true;
 		foreach ($constantIntegers as $constantInteger) {
 			$mode = $constantInteger->getValue();
 			if ($mode === 0 || ($mode & 0xFFFF) === self::FETCH_KEY_PAIR || ($mode & self::FETCH_GROUP) !== 0) {
-				return null;
+				$isList = false;
+				break;
 			}
 		}
 
 		$variant = ParametersAcceptorSelector::selectFromArgs($scope, $args, $methodReflection->getVariants());
 		$returnType = $variant->getReturnType();
+		$canBeFalse = !$returnType->isFalse()->no();
+
+		if ($isList) {
+			$resultType = TypeCombinator::intersect(
+				new ArrayType(new IntegerType(), new MixedType()),
+				new AccessoryArrayListType(),
+			);
+		} else {
+			$resultType = new ArrayType(new MixedType(), new MixedType());
+		}
 
-		$listType = TypeCombinator::intersect(
-			new ArrayType(new IntegerType(), new MixedType()),
-			new AccessoryArrayListType(),
-		);
-
-		if (!$returnType->isFalse()->no()) {
-			return TypeCombinator::union($listType, new ConstantBooleanType(false));
+		if ($canBeFalse) {
+			return TypeCombinator::union($resultType, new ConstantBooleanType(false));
 		}
 
-		return $listType;
+		return $resultType;
 	}
 
 }