[Psalm] Fix filter function refinment bug.

docker-compose.yml

@@ -0,0 +1,10 @@
+version: '3.6'
+services:
+  php:
+    container_name: php_functional
+    build:
+      context: ./docker/php
+      dockerfile: Dockerfile
+    tty: true
+    volumes:
+      - ./:/app

docker/php/Dockerfile

@@ -0,0 +1,30 @@
+FROM php:8.0-cli
+
+ADD https://github.com/mlocati/docker-php-extension-installer/releases/latest/download/install-php-extensions /usr/local/bin/
+RUN chmod +x /usr/local/bin/install-php-extensions
+
+RUN apt-get update -y && apt-get install -y curl unzip
+
+RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/bin --filename=composer --quiet
+
+RUN install-php-extensions xdebug
+
+COPY ./ "$PHP_INI_DIR/conf.d"
+
+ARG HOST_UID=1000
+ARG HOST_GID=1000
+ARG HOST_USER=docker-user
+ARG HOST_GROUP=docker-group
+
+RUN echo '%sudonopswd ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers \
+    && groupadd -g $HOST_GID $HOST_GROUP \
+    && groupadd sudonopswd \
+    && useradd -m -l -g $HOST_GROUP -u $HOST_UID $HOST_USER \
+    && usermod -aG sudo $HOST_USER \
+    && usermod -aG sudonopswd $HOST_USER \
+    && chown -R $HOST_USER:$HOST_GROUP /opt \
+    && chmod 755 /opt
+
+USER $HOST_USER
+
+WORKDIR /app

src/Fp/Psalm/Util/TypeRefinement/CollectionTypeExtractor.php

@@ -83,7 +83,7 @@ private static function fromSeq(Atomic $atomic): Option
             ->filter(fn($a) => $a instanceof TGenericObject)
             ->filter(fn($a) => classOf($a->value, Seq::class) || classOf($a->value, NonEmptySeq::class))
             ->filter(fn($a) => 1 === count($a->type_params))
-            ->map(fn($a) => new CollectionTypeParams(Type::getArrayKey(), $a->type_params[1]));
+            ->map(fn($a) => new CollectionTypeParams(Type::getArrayKey(), $a->type_params[0]));
     }
 
     /**
@@ -95,7 +95,7 @@ private static function fromSet(Atomic $atomic): Option
             ->filter(fn($a) => $a instanceof TGenericObject)
             ->filter(fn($a) => classOf($a->value, Set::class) || classOf($a->value, NonEmptySet::class))
             ->filter(fn($a) => 1 === count($a->type_params))
-            ->map(fn($a) => new CollectionTypeParams(Type::getArrayKey(), $a->type_params[1]));
+            ->map(fn($a) => new CollectionTypeParams(Type::getArrayKey(), $a->type_params[0]));
     }
 
     /**