Numeric not handling trailing zeros (#3371)

```tsp
const a = 100.0
```

was getting into an infinite loop

.chronus/changes/fix-numeric-not-handling-trailing-zeros-2024-4-16-2-43-25.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/compiler"
+---
+
+Numeric not handling trailing zeros and causing freeze(e.g. `const a = 100.0`)

packages/compiler/src/core/numeric.ts

@@ -118,14 +118,10 @@ function parse(original: string): InternalData {
     }
 
     let end = stringValue.length;
-    while (stringValue[end - 1] === "0") {
-      if (end < adjustedPointIndex) {
-        // if we are looking at a zero before the decimal point, we need to decrease the exponent
-        exp++;
-      } else {
-        end--;
-      }
+    while (stringValue[end - 1] === "0" && end > adjustedPointIndex) {
+      end--;
     }
+
     try {
       stringValue = stringValue.slice(0, end);
       stringValue = stringValue + "0".repeat(Math.max(exp - stringValue.length, 0)); // add remaining zeros for cases like 3e30

packages/compiler/test/core/numeric.test.ts

@@ -22,7 +22,7 @@ describe("parsing", () => {
 
   describe("invalid number", () => {
     // cspell: ignore babc
-    it.each(["0babc", "0xGHI", "0o999", "a123", "1d.3"])("%s", (a) => {
+    it.each(["0babc", "0xGHI", "0o999", "a123", "1d.3", "1.2.3"])("%s", (a) => {
       expect(() => Numeric(a)).toThrow(`Invalid numeric value: ${a}`);
     });
   });
@@ -39,6 +39,24 @@ describe("parsing", () => {
     it("simple decimal", () => {
       expectNumericData("123.456", 123456n, 3);
     });
+
+    describe("decimal with trailing zeros", () => {
+      it.each([
+        ["1.0", 1n, 1],
+        ["10", 10n, 2],
+        ["10.0", 10n, 2],
+        ["10.00000", 10n, 2],
+        ["100.0", 100n, 3],
+        ["100", 100n, 3],
+        ["1000.0", 1000n, 4],
+        ["1000000000", 1000000000n, 10],
+        ["1000000000.0", 1000000000n, 10],
+        ["1000000000.00000", 1000000000n, 10],
+      ])(`%s`, (a, b, c) => {
+        expectNumericData(a, b, c);
+      });
+    });
+
     it("negative decimal", () => {
       expectNumericData("-123.456", 123456n, 3, -1);
     });