Allow zero-width big-endian data for toBeHex and allow widths fo toBeArray (#5025).

Author: ricmoo

src.ts/utils/maths.ts

@@ -191,6 +191,10 @@ export function toBeHex(_value: BigNumberish, _width?: Numeric): string {
         if (result.length % 2) { result = "0" + result; }
     } else {
         const width = getNumber(_width, "width");
+
+        // Special case when both value and width are 0 (see: #5025)
+        if (width === 0 && value === BN_0) { return "0x"; }
+
         assert(width * 2 >= result.length, `value exceeds width (${ width } bytes)`, "NUMERIC_FAULT", {
             operation: "toBeHex",
             fault: "overflow",
@@ -208,14 +212,29 @@ export function toBeHex(_value: BigNumberish, _width?: Numeric): string {
 /**
  *  Converts %%value%% to a Big Endian Uint8Array.
  */
-export function toBeArray(_value: BigNumberish): Uint8Array {
+export function toBeArray(_value: BigNumberish, _width?: Numeric): Uint8Array {
     const value = getUint(_value, "value");
 
-    if (value === BN_0) { return new Uint8Array([ ]); }
+    if (value === BN_0) {
+        const width = (_width != null) ? getNumber(_width, "width"): 0;
+        return new Uint8Array(width);
+    }
 
     let hex = value.toString(16);
     if (hex.length % 2) { hex = "0" + hex; }
 
+    if (_width != null) {
+        const width = getNumber(_width, "width");
+
+        while (hex.length < (width * 2)) { hex = "00" + hex; }
+
+        assert((width * 2) === hex.length, `value exceeds width (${ width } bytes)`, "NUMERIC_FAULT", {
+            operation: "toBeArray",
+            fault: "overflow",
+            value: _value
+        });
+    }
+
     const result = new Uint8Array(hex.length / 2);
     for (let i = 0; i < result.length; i++) {
         const offset = i * 2;