patch 8.2.2842: Vim9: skip argument to searchpair() is not compiled

Problem:    Vim9: skip argument to searchpair() is not compiled.
Solution:   Add VAR_INSTR.
diff --git a/src/eval.c b/src/eval.c
index f254549..bf9e8ee 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -309,6 +309,10 @@
 		return FAIL;
 	}
     }
+    else if (expr->v_type == VAR_INSTR)
+    {
+	return exe_typval_instr(expr, rettv);
+    }
     else
     {
 	s = tv_get_string_buf_chk(expr, buf);
@@ -1510,6 +1514,7 @@
 	    case VAR_SPECIAL:
 	    case VAR_JOB:
 	    case VAR_CHANNEL:
+	    case VAR_INSTR:
 		break;
 
 	    case VAR_BLOB:
@@ -4084,6 +4089,7 @@
 	case VAR_SPECIAL:
 	case VAR_JOB:
 	case VAR_CHANNEL:
+	case VAR_INSTR:
 	    if (verbose)
 		emsg(_(e_cannot_index_special_variable));
 	    return FAIL;
@@ -4177,6 +4183,7 @@
 	case VAR_SPECIAL:
 	case VAR_JOB:
 	case VAR_CHANNEL:
+	case VAR_INSTR:
 	    break; // not evaluating, skipping over subscript
 
 	case VAR_NUMBER:
@@ -5067,6 +5074,11 @@
 	    }
 	    break;
 
+	case VAR_INSTR:
+	    *tofree = NULL;
+	    r = (char_u *)"instructions";
+	    break;
+
 	case VAR_FLOAT:
 #ifdef FEAT_FLOAT
 	    *tofree = NULL;
@@ -5987,6 +5999,7 @@
 	case VAR_SPECIAL:
 	case VAR_JOB:
 	case VAR_CHANNEL:
+	case VAR_INSTR:
 	    copy_tv(from, to);
 	    break;
 	case VAR_LIST: