patch 8.2.2602: Vim9: continue doesn't work if :while is very first command

Problem:    Vim9: continue doesn't work if :while is very first command.
            (Yegappan Lakshmanan)
Solution:   Add one to the continue instruction index.
diff --git a/src/vim9execute.c b/src/vim9execute.c
index f8470f5..b2c28a3 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -30,7 +30,7 @@
     int	    tcd_finally_idx;	// instruction of the :finally block or zero
     int	    tcd_endtry_idx;	// instruction of the :endtry
     int	    tcd_caught;		// catch block entered
-    int	    tcd_cont;		// :continue encountered, jump here
+    int	    tcd_cont;		// :continue encountered, jump here (minus one)
     int	    tcd_return;		// when TRUE return from end of :finally
 } trycmd_T;
 
@@ -2757,7 +2757,9 @@
 		    {
 			trycmd = ((trycmd_T *)trystack->ga_data)
 							+ trystack->ga_len - i;
-			trycmd->tcd_cont = iidx;
+			// Add one to tcd_cont to be able to jump to
+			// instruction with index zero.
+			trycmd->tcd_cont = iidx + 1;
 			iidx = trycmd->tcd_finally_idx == 0
 			    ? trycmd->tcd_endtry_idx : trycmd->tcd_finally_idx;
 		    }
@@ -2811,7 +2813,7 @@
 			if (trycmd->tcd_cont != 0)
 			    // handling :continue: jump to outer try block or
 			    // start of the loop
-			    ectx.ec_iidx = trycmd->tcd_cont;
+			    ectx.ec_iidx = trycmd->tcd_cont - 1;
 		    }
 		}
 		break;