Only attempt to cast heal other/resurrect with a target

Source/diablo.cpp

@@ -1796,15 +1796,23 @@ int DiabloMain(int argc, char **argv)
 bool TryIconCurs()
 {
 	if (pcurs == CURSOR_RESURRECT) {
-		NetSendCmdParam1(true, CMD_RESURRECT, pcursplr);
-		NewCursor(CURSOR_HAND);
-		return true;
+		if (pcursplr != -1) {
+			NetSendCmdParam1(true, CMD_RESURRECT, pcursplr);
+			NewCursor(CURSOR_HAND);
+			return true;
+		}
+
+		return false;
 	}
 
 	if (pcurs == CURSOR_HEALOTHER) {
-		NetSendCmdParam1(true, CMD_HEALOTHER, pcursplr);
-		NewCursor(CURSOR_HAND);
-		return true;
+		if (pcursplr != -1) {
+			NetSendCmdParam1(true, CMD_HEALOTHER, pcursplr);
+			NewCursor(CURSOR_HAND);
+			return true;
+		}
+
+		return false;
 	}
 
 	if (pcurs == CURSOR_TELEKINESIS) {