fix duplicate incorrect arity error

compiler-core/src/type_/pattern.rs

···
                     }
                 };
 
+                let mut incorrect_arity_error = false;
                 match constructor.field_map() {
                     // The fun has a field map so labelled arguments may be present and need to be reordered.
                     Some(field_map) => {
···
                             location,
                             IncorrectArityContext::Pattern,
                         ) {
-                            {
-                                self.problems.error(error);
-                                self.error_encountered = true;
-                            };
+                            incorrect_arity_error = true;
+                            self.problems.error(error);
+                            self.error_encountered = true;
                         }
                     }
 
···
                             self.set_subject_variable_variant(variable_to_infer, inferred_variant);
                         }
 
-                        if args.len() != pattern_args.len() {
+                        // We're emitting the incorrect arity error only if we haven't emitted
+                        // one already. This might happen when we can't reorder the field map
+                        // of a constructor because there's not enough labels.
+                        if args.len() != pattern_args.len() && !incorrect_arity_error {
                             self.error(Error::IncorrectArity {
                                 labels: vec![],
                                 location,

compiler-core/src/type_/tests/errors.rs

···
 "
     );
 }
+
+// https://github.com/gleam-lang/gleam/issues/4693
+#[test]
+fn pattern_with_incorrect_arity() {
+    assert_module_error!(
+        "
+pub type Pokemon { Pokemon(name: String, id: Int) }
+
+pub fn main() {
+  case todo {
+    Pokemon(name:) -> todo
+  }
+}
+"
+    );
+}

compiler-core/src/type_/tests/snapshots/gleam_core__type___tests__errors__pattern_with_incorrect_arity.snap

···
+---
+source: compiler-core/src/type_/tests/errors.rs
+expression: "\npub type Pokemon { Pokemon(name: String, id: Int) }\n\npub fn main() {\n  case todo {\n    Pokemon(name:) -> todo\n  }\n}\n"
+---
+----- SOURCE CODE
+
+pub type Pokemon { Pokemon(name: String, id: Int) }
+
+pub fn main() {
+  case todo {
+    Pokemon(name:) -> todo
+  }
+}
+
+
+----- ERROR
+error: Incorrect arity
+  ┌─ /src/one/two.gleam:6:5
+  │
+6 │     Pokemon(name:) -> todo
+  │     ^^^^^^^^^^^^^^ Expected 2 arguments, got 1
+
+This pattern accepts these additional labelled arguments:
+
+  - id