Fix error when HashMap.remove on uninitialized HashMap (#1629)

* HashMap: test removal on uninitialized

* HashMap.remove_entry_for_key: return false on unintialized

* test: switch to temp_init

* release note

lib/std/collections/hashmap.c3

@@ -482,6 +482,7 @@ fn void HashMap.free_internal(&map, void* ptr) @inline @private
 
 fn bool HashMap.remove_entry_for_key(&map, Key key) @private
 {
+	if (!map.count) return false;
 	uint hash = rehash(key.hash());
 	uint i = index_for(hash, map.table.len);
 	Entry* prev = map.table[i];

releasenotes.md

@@ -12,6 +12,7 @@
 - Fix issue writing a single byte in the WriteBuffer
 - A distinct inline pointer type can now participate in pointer arithmetics.
 - Support &a[0] returning the distinct type when applying it to a distinct of a pointer.
+- Fix error when calling `HashMap.remove` on uninitialized `HashMap`.
 
 ### Stdlib changes
 - Add `io::MultiReader`, `io::MultiWriter`, and `io::TeeReader` structs.

test/unit/stdlib/collections/map.c3

@@ -53,4 +53,14 @@ fn void map()
         assert(tc.key == list[i].key);
         assert(tc.value == list[i].value);
     }
-}
+}
+
+fn void map_remove()
+{
+	Map m;
+	assert(!@ok(m.remove("A")));
+	m.temp_init();
+	assert(!@ok(m.remove("A")));
+	m.set("A", 0);
+	assert(@ok(m.remove("A")));
+}