obs-webrtc: Add additional error messaging for WHIP output

Adding to the previous commit, let's also use obs_output_set_last_error
to provide localized error messages to the user if we run into these
failure cases.

plugins/obs-webrtc/data/locale/en-US.ini

@@ -1,3 +1,6 @@
 Output.Name="WHIP Output"
 Service.Name="WHIP Service"
 Service.BearerToken="Bearer Token"
+
+Error.InvalidSDP="WHIP server responded with invalid SDP: %1"
+Error.NoRemoteDescription="Failed to set remote description: %1"

plugins/obs-webrtc/whip-output.cpp

@@ -407,12 +407,24 @@ bool WHIPOutput::Connect()
 		do_log(LOG_ERROR, "WHIP server responded with invalid SDP: %s",
 		       err.what());
 		cleanup();
+		struct dstr error_message;
+		dstr_init_copy(&error_message,
+			       obs_module_text("Error.InvalidSDP"));
+		dstr_replace(&error_message, "%1", err.what());
+		obs_output_set_last_error(output, error_message.array);
+		dstr_free(&error_message);
 		obs_output_signal_stop(output, OBS_OUTPUT_CONNECT_FAILED);
 		return false;
 	} catch (const std::exception &err) {
 		do_log(LOG_ERROR, "Failed to set remote description: %s",
 		       err.what());
 		cleanup();
+		struct dstr error_message;
+		dstr_init_copy(&error_message,
+			       obs_module_text("Error.NoRemoteDescription"));
+		dstr_replace(&error_message, "%1", err.what());
+		obs_output_set_last_error(output, error_message.array);
+		dstr_free(&error_message);
 		obs_output_signal_stop(output, OBS_OUTPUT_CONNECT_FAILED);
 		return false;
 	}