fix: error message with getLens()

Author: waitingsong

src/lib/config.ts

@@ -13,7 +13,7 @@ revLookup['-'.charCodeAt(0)] = 62
 revLookup['_'.charCodeAt(0)] = 63
 
 export const ErrorMsg = {
-  base64Invalidlength: 'Invalid string. Length must be a multiple of 4',
+  base64Invalidlength: 'Invalid string. Length must be a multiple of 4 and positive',
   encodeInvalidParam: 'Invalid value of parameter of encode(), should be string|number|bigint',
   fromArrayBufferInvalidParam: 'Invalid input, should be ArrayBuffer or Uint8Array',
   notString: 'Invalid value of parameter, should be string',

src/lib/to_buffer.ts

@@ -51,7 +51,7 @@ export function getLens(input: string): [number, number] {
   const len = input.length
 
   if (len & 3) {
-    throw new Error(ErrorMsg.encodeInvalidParam)
+    throw new Error(ErrorMsg.base64Invalidlength)
   }
 
   // Trim off extra bytes after placeholder bytes are found