patch 9.0.0498: various small issues

Problem:    Various small issues.
Solution:   Various small fixes.
diff --git a/src/debugger.c b/src/debugger.c
index 235d493..4a32550 100644
--- a/src/debugger.c
+++ b/src/debugger.c
@@ -135,7 +135,7 @@
 	    ignore_script = TRUE;
 	}
 
-	// don't debug any function call, e.g. from an expresion mapping
+	// don't debug any function call, e.g. from an expression mapping
 	n = debug_break_level;
 	debug_break_level = -1;