patch 9.0.0360: crash when invalid line number on :for is ignored

Problem:    Crash when invalid line number on :for is ignored.
Solution:   Do not check breakpoint for non-existing line.
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index ae1f195..0b6b217 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -1068,7 +1068,7 @@
 
 		    // Check for the next breakpoint at or after the ":while"
 		    // or ":for".
-		    if (breakpoint != NULL)
+		    if (breakpoint != NULL && lines_ga.ga_len > current_line)
 		    {
 			*breakpoint = dbg_find_breakpoint(
 			       getline_equal(fgetline, cookie, getsourceline),