[planbuilder] nil database doesn't panic building procedure call

Author: max-hoffman

enginetest/enginetests.go

@@ -4877,6 +4877,7 @@ func TestNoDatabaseSelected(t *testing.T, harness Harness) {
 	AssertErrWithCtx(t, e, harness, ctx, "create table a (b int primary key)", nil, sql.ErrNoDatabaseSelected)
 	AssertErrWithCtx(t, e, harness, ctx, "show tables", nil, sql.ErrNoDatabaseSelected)
 	AssertErrWithCtx(t, e, harness, ctx, "show triggers", nil, sql.ErrNoDatabaseSelected)
+	AssertErrWithCtx(t, e, harness, ctx, "call non_existent_proc()", nil, sql.ErrNoDatabaseSelected)
 
 	_, _, _, err := e.Query(ctx, "ROLLBACK")
 	require.NoError(t, err)

sql/planbuilder/proc.go

@@ -311,6 +311,9 @@ func (b *Builder) buildCall(inScope *scope, c *ast.Call) (outScope *scope) {
 	} else if b.ctx.GetCurrentDatabase() != "" {
 		db = b.currentDb()
 	}
+	if db == nil {
+		b.handleErr(sql.ErrNoDatabaseSelected.New())
+	}
 
 	var proc *plan.Procedure
 	var innerQFlags *sql.QueryFlags