Add Danger check for Decimal(exactly: aBigUInt) which compiles but crashes at runtime

dangerfile.js

@@ -7,6 +7,7 @@ if (danger.github) {
     warnClosureStronglyCapturesSelf()
     failUsingNSLocalizedStringWithoutR()
     failIfRemoveAnyRealmSchemaMigrationBlock()
+    failIfUseDecimalExactlyInit()
     checkForSpacesInOtherwiseEmptyLines()
 }
 
@@ -54,6 +55,17 @@ function failIfRemoveAnyRealmSchemaMigrationBlock() {
     })
 }
 
+//Can't use Decimal(exactly: aBigUint). It compiles but crashes at runtime
+function failIfUseDecimalExactlyInit() {
+    modifiedSwiftFiles().forEach(each => {
+        danger.git.diffForFile(each).then(diff => {
+            if (diff.added.includes("Decimal(exactly:")) {
+                fail(each + ": Must not use Decimal(exactly:), especially on BigUInt. Use Decimal(string: aBigUint.description) instead")
+            }
+        })
+    })
+}
+
 function checkForSpacesInOtherwiseEmptyLines() {
     modifiedSwiftFiles().forEach(each => {
         danger.git.diffForFile(each).then(diff => {