avm2: Stub for Error.getErrorMessage

core/src/avm2/globals/Error.as

@@ -11,6 +11,8 @@ package {
             };
         }
 
+        public static native function getErrorMessage(id:int):String;
+
         [Ruffle(NativeAccessible)]
         public var name:String = "Error";
 

core/src/avm2/globals/error.rs

@@ -1,9 +1,22 @@
 use crate::avm2::activation::Activation;
 pub use crate::avm2::object::error_allocator;
+use crate::avm2::parameters::ParametersExt;
 use crate::avm2::string::AvmString;
 use crate::avm2::value::Value;
 use crate::avm2::Error;
-use crate::PlayerMode;
+use crate::{avm2_stub_method, PlayerMode};
+
+pub fn get_error_message<'gc>(
+    activation: &mut Activation<'_, 'gc>,
+    _this: Value<'gc>,
+    args: &[Value<'gc>],
+) -> Result<Value<'gc>, Error<'gc>> {
+    avm2_stub_method!(activation, "Error", "getErrorMessage");
+
+    let id = args.get_i32(0);
+    let message = format!("Error #{id}");
+    Ok(AvmString::new_utf8(activation.gc(), message).into())
+}
 
 pub fn get_stack_trace<'gc>(
     activation: &mut Activation<'_, 'gc>,

tests/tests/swfs/avm2/error_geterrormessage/Test.as

@@ -0,0 +1,19 @@
+package {
+	import flash.display.Sprite;
+
+	public class Test extends Sprite {
+		public function Test() {
+			trace(Error.getErrorMessage(-1));
+			trace(Error.getErrorMessage(0));
+			trace(Error.getErrorMessage(1));
+			trace(Error.getErrorMessage(42));
+			trace(Error.getErrorMessage(100));
+			// TODO:
+			// Error #1000: The system is out of memory.
+			// trace(Error.getErrorMessage(1000));
+			// Error #1042: Not an ABC file.  major_version=%1 minor_version=%2.
+			// trace(Error.getErrorMessage(1042));
+			trace(Error.getErrorMessage(10000));
+		}
+	}
+}

tests/tests/swfs/avm2/error_geterrormessage/output.txt

@@ -0,0 +1,6 @@
+Error #-1
+Error #0
+Error #1
+Error #42
+Error #100
+Error #10000

tests/tests/swfs/avm2/error_geterrormessage/test.toml

@@ -0,0 +1 @@
+num_frames = 1