go/vt/vtgate: fix nilness issues (#14685)

Author: mdlayher

go/vt/vtgate/engine/vindex_lookup.go

@@ -227,10 +227,6 @@ func (vr *VindexLookup) executeBatch(ctx context.Context, vcursor VCursor, ids [
 	} else {
 		result, err = vcursor.ExecutePrimitive(ctx, vr.Lookup, bindVars, false)
 	}
-	if err != nil {
-		return nil, err
-	}
-
 	if err != nil {
 		return nil, vterrors.Wrapf(err, "failed while running the lookup query")
 	}

go/vt/vtgate/evalengine/api_coerce.go

@@ -48,7 +48,7 @@ func CoerceTypes(v1, v2 Type) (out Type, err error) {
 	switch {
 	case sqltypes.IsTextOrBinary(v1.Type()) && sqltypes.IsTextOrBinary(v2.Type()):
 		mergedCollation, _, _, ferr := mergeCollations(typedCoercionCollation(v1.Type(), v1.Collation()), typedCoercionCollation(v2.Type(), v2.Collation()), v1.Type(), v2.Type())
-		if err != nil {
+		if ferr != nil {
 			return Type{}, ferr
 		}
 		out.collation = mergedCollation.Collation

go/vt/vtgate/planbuilder/operator_transformers.go

@@ -251,9 +251,6 @@ func transformAggregator(ctx *plancontext.PlanningContext, op *operators.Aggrega
 		})
 	}
 
-	if err != nil {
-		return nil, err
-	}
 	oa.truncateColumnCount = op.ResultColumns
 	return oa, nil
 }
@@ -431,9 +428,6 @@ func routeToEngineRoute(ctx *plancontext.PlanningContext, op *operators.Route, h
 
 	rp := newRoutingParams(ctx, op.Routing.OpCode())
 	op.Routing.UpdateRoutingParams(ctx, rp)
-	if err != nil {
-		return nil, err
-	}
 
 	e := &engine.Route{
 		TableName:           strings.Join(tableNames, ", "),

go/vt/vtgate/planbuilder/operators/query_planning.go

@@ -55,8 +55,8 @@ func planQuery(ctx *plancontext.PlanningContext, root Operator) (output Operator
 // If we can push it under a route - done.
 // If we can't, we will instead expand the Horizon into
 // smaller operators and try to push these down as far as possible
-func runPhases(ctx *plancontext.PlanningContext, root Operator) (op Operator, err error) {
-	op = root
+func runPhases(ctx *plancontext.PlanningContext, root Operator) (Operator, error) {
+	op := root
 
 	p := phaser{}
 	for phase := p.next(ctx); phase != DONE; phase = p.next(ctx) {
@@ -66,19 +66,14 @@ func runPhases(ctx *plancontext.PlanningContext, root Operator) (op Operator, er
 		}
 
 		op = phase.act(ctx, op)
-		if err != nil {
-			return nil, err
-		}
 
+		var err error
 		op, err = runRewriters(ctx, op)
 		if err != nil {
 			return nil, err
 		}
 
 		op = compact(ctx, op)
-		if err != nil {
-			return nil, err
-		}
 	}
 
 	return addGroupByOnRHSOfJoin(op), nil
@@ -222,7 +217,7 @@ func pushProjectionToOuter(ctx *plancontext.PlanningContext, p *Projection, sq *
 		return p, NoRewrite
 	}
 
-	if !reachedPhase(ctx, subquerySettling) || err != nil {
+	if !reachedPhase(ctx, subquerySettling) {
 		return p, NoRewrite
 	}
 

go/vt/vtgate/planbuilder/operators/vindex.go

@@ -148,15 +148,12 @@ func (v *Vindex) AddPredicate(ctx *plancontext.PlanningContext, expr sqlparser.E
 		}
 
 		// check RHS
-		var err error
 		if sqlparser.IsValue(comparison.Right) || sqlparser.IsSimpleTuple(comparison.Right) {
 			v.Value = comparison.Right
 		} else {
 			panic(vterrors.VT09018(wrongWhereCond + " (rhs is not a value)"))
 		}
-		if err != nil {
-			panic(vterrors.VT09018(wrongWhereCond+": %v", err))
-		}
+
 		v.OpCode = engine.VindexMap
 		v.Table.Predicates = append(v.Table.Predicates, e)
 	}