[#323] client: Use constant for error message

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

client/common.go

@@ -69,6 +69,7 @@ func (x prmCommonMeta) writeToMetaHeader(h *v2session.RequestMetaHeader) {
 const (
 	panicMsgMissingContext   = "missing context"
 	panicMsgMissingContainer = "missing container"
+	panicMsgMissingObject    = "missing object"
 )
 
 // groups all the details required to send a single request and process a response to it.

client/object_delete.go

@@ -131,7 +131,7 @@ func (c *Client) ObjectDelete(ctx context.Context, prm PrmObjectDelete) (*ResObj
 	case prm.addr.GetContainerID() == nil:
 		panic(panicMsgMissingContainer)
 	case prm.addr.GetObjectID() == nil:
-		panic("missing object")
+		panic(panicMsgMissingObject)
 	}
 
 	// form request body

client/object_get.go

@@ -319,7 +319,7 @@ func (c *Client) ObjectGetInit(ctx context.Context, prm PrmObjectGet) (*ObjectRe
 	case !prm.cnrSet:
 		panic(panicMsgMissingContainer)
 	case !prm.objSet:
-		panic("missing object")
+		panic(panicMsgMissingObject)
 	}
 
 	var (
@@ -458,7 +458,7 @@ func (c *Client) ObjectHead(ctx context.Context, prm PrmObjectHead) (*ResObjectH
 	case !prm.cnrSet:
 		panic(panicMsgMissingContainer)
 	case !prm.objSet:
-		panic("missing object")
+		panic(panicMsgMissingObject)
 	}
 
 	var (
@@ -729,7 +729,7 @@ func (c *Client) ObjectRangeInit(ctx context.Context, prm PrmObjectRange) (*Obje
 	case !prm.cnrSet:
 		panic(panicMsgMissingContainer)
 	case !prm.objSet:
-		panic("missing object")
+		panic(panicMsgMissingObject)
 	case prm.ln == 0:
 		panic("zero range length")
 	}

client/object_hash.go

@@ -161,7 +161,7 @@ func (c *Client) ObjectHash(ctx context.Context, prm PrmObjectHash) (*ResObjectH
 	case prm.addr.GetContainerID() == nil:
 		panic(panicMsgMissingContainer)
 	case prm.addr.GetObjectID() == nil:
-		panic("missing object")
+		panic(panicMsgMissingObject)
 	case len(prm.body.GetRanges()) == 0:
 		panic("missing ranges")
 	}