Can no longer export negative amount

src/Constants.ts

@@ -246,6 +246,7 @@ export const CONSTANTS: IMap<any> = {
 
     Corp
     * Self-fund with an invalid name no longer takes away 150b anyway.
+    * Can no longer export negative amount
 
     Misc.
     * ls now correctly lists all files.

src/Corporation/ui/CorporationUIEventHandler.js

@@ -320,7 +320,7 @@ export class CorporationEventHandler {
                     return false;
                 }
 
-                if (temp == null || isNaN(temp)) {
+                if (temp == null || isNaN(temp) || temp < 0) {
                     dialogBoxCreate("Invalid amount entered for export");
                     return;
                 }