patch 8.2.4358: Vim9: line number of exception is not set

Problem:    Vim9: line number of exception is not set.
Solution:   Set the line number before throwing an exception. (closes #9755)

src/testdir/test_vim9_script.vim

@@ -1057,6 +1057,18 @@ def Test_try_catch_skipped()
   assert_match("NEWLIST size 0\n", instr)
 enddef
 
+def Test_throw_line_number()
+  def Func()
+    eval 1 + 1
+    eval 2 + 2
+    throw 'exception'
+  enddef
+  try
+    Func()
+  catch /exception/
+    assert_match('line 3', v:throwpoint)
+  endtry
+enddef
 
 
 def Test_throw_vimscript()

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4358,
 /**/
     4357,
 /**/

src/vim9execute.c

@@ -3826,6 +3826,7 @@ exec_instructions(ectx_T *ectx)
 			}
 		    }
 
+		    SOURCING_LNUM = iptr->isn_lnum;
 		    if (throw_exception(tv->vval.v_string, ET_USER, NULL)
 								       == FAIL)
 		    {