Fix self-analysis errors surfaced by the foreach non-empty narrowing

The unconditional non-empty narrowing makes phpstan-src's own foreach bodies
provably entered, which surfaces six latent issues under phpstan-strict-rules:

- foreach.valueOverwrite: three inner loops whose value variable now shadows a
  definitely-defined outer variable are renamed ($internalError -> $error,
  $file -> $sourceFile, $i -> $j).
- offsetAccess.nonArray: three [$k, $v] = $this->unsealed destructurings on a
  list<Type>|null property gain an explicit null guard throwing
  ShouldNotHappenException, matching the file's existing impossible-state style.

Author: zonuexe

src/Command/AnalyseCommand.php

@@ -477,8 +477,8 @@ protected function execute(InputInterface $input, OutputInterface $output): int
 		if ($generateBaselineFile !== null) {
 			$this->runDiagnoseExtensions($container, $inceptionResult->getErrorOutput(), $analysisResult->getProcessedFiles());
 			if (count($internalErrorsTuples) > 0) {
-				foreach ($internalErrorsTuples as [$internalError]) {
-					$inceptionResult->getStdOutput()->writeLineFormatted($internalError->getMessage());
+				foreach ($internalErrorsTuples as [$error]) {
+					$inceptionResult->getStdOutput()->writeLineFormatted($error->getMessage());
 					$inceptionResult->getStdOutput()->writeLineFormatted('');
 				}
 

src/Reflection/BetterReflection/SourceLocator/OptimizedDirectorySourceLocator.php

@@ -134,16 +134,16 @@ public function locateIdentifier(Reflector $reflector, Identifier $identifier):
 		if ($identifier->isClass()) {
 			$fetchedClassNode = null;
 			$fetchedFile = null;
-			foreach ($files as $file) {
-				$fetchedClassNodes = $this->fileNodesFetcher->fetchNodes($file)->getClassNodes();
+			foreach ($files as $sourceFile) {
+				$fetchedClassNodes = $this->fileNodesFetcher->fetchNodes($sourceFile)->getClassNodes();
 
 				if (!array_key_exists($identifierName, $fetchedClassNodes)) {
 					return null;
 				}
 
 				/** @var FetchedNode<Node\Stmt\ClassLike> $fetchedClassNode */
 				$fetchedClassNode = current($fetchedClassNodes[$identifierName]);
-				$fetchedFile = $file;
+				$fetchedFile = $sourceFile;
 			}
 
 			[$reflectionCacheKey, $variableCacheKey] = $this->getCacheKeys($fetchedFile, $identifier);

src/Type/Constant/ConstantArrayType.php

@@ -811,7 +811,11 @@ public function isSuperTypeOf(Type $type): IsSuperTypeOfResult
 						continue;
 					}
 
-					[$thisUnsealedKey, $thisUnsealedValue] = $this->unsealed;
+					$thisUnsealed = $this->unsealed;
+					if ($thisUnsealed === null) {
+						throw new ShouldNotHappenException();
+					}
+					[$thisUnsealedKey, $thisUnsealedValue] = $thisUnsealed;
 					$keyCheck = $thisUnsealedKey->isSuperTypeOf($typeKey);
 					if ($keyCheck->no()) {
 						if ($type->isOptionalKey($i)) {
@@ -835,8 +839,13 @@ public function isSuperTypeOf(Type $type): IsSuperTypeOfResult
 					if ($thisUnsealedness->no()) {
 						$results[] = IsSuperTypeOfResult::createMaybe();
 					} else {
-						[$thisUnsealedKey, $thisUnsealedValue] = $this->unsealed;
-						[$typeUnsealedKey, $typeUnsealedValue] = $type->unsealed;
+						$thisUnsealed = $this->unsealed;
+						$typeUnsealed = $type->unsealed;
+						if ($thisUnsealed === null || $typeUnsealed === null) {
+							throw new ShouldNotHappenException();
+						}
+						[$thisUnsealedKey, $thisUnsealedValue] = $thisUnsealed;
+						[$typeUnsealedKey, $typeUnsealedValue] = $typeUnsealed;
 						$results[] = $thisUnsealedKey->isSuperTypeOf($typeUnsealedKey);
 						$results[] = $thisUnsealedValue->isSuperTypeOf($typeUnsealedValue);
 					}

src/Type/UnionType.php

@@ -239,9 +239,9 @@ public function accepts(Type $type, bool $strictTypes): AcceptsResult
 		}
 		if ($commonReasons !== null && count($commonReasons) > 0) {
 			$decorated = [];
-			foreach (array_keys($innerAccepts) as $i) {
+			foreach (array_keys($innerAccepts) as $j) {
 				foreach ($commonReasons as $reason) {
-					$decorated[] = sprintf('Type #%d from the union: %s', $i + 1, $reason);
+					$decorated[] = sprintf('Type #%d from the union: %s', $j + 1, $reason);
 				}
 			}
 			$result = new AcceptsResult($result->result, $decorated);