Update warning message

src/pages/Send/index.js

@@ -543,7 +543,7 @@ class Send extends Component {
       const missingCurrencyValue = !inputValue ? inputLabel : outputLabel;
       nextStepMessage = `Enter a ${missingCurrencyValue} value to continue.`;
     } else if (inputIsZero || outputIsZero) {
-      nextStepMessage = 'Amount cannot be zero.';
+      nextStepMessage = 'No liquidity.';
     } else if (this.isUnapproved()) {
       nextStepMessage = 'Please unlock token to continue.';
     } else if (!recipient) {

src/pages/Swap/index.js

@@ -534,7 +534,7 @@ class Swap extends Component {
     if (inputIsZero || outputIsZero) {
       return (
         <div className="swap__summary-wrapper">
-          <div>Amount cannot be zero.</div>
+          <div>No liquidity.</div>
         </div>
       )
     }