Add template for requesting improvements to errors (#16918)

* Add template for requesting improvements to errors

* Default title, labels (devex + language/), add dylant-da as assignee

.github/ISSUE_TEMPLATE/error_improvement.md

@@ -0,0 +1,49 @@
+---
+name: Error Message Improvement
+about: Request an improvement to error messages or diagnostics for Daml.
+title: "[Error Message Improvement] "
+labels: ["developer-experience", "language/error-message-improvement"]
+assignees:
+  - dylant-da
+
+---
+
+<!--
+I confirm that, if this is a request that has security implications, I already contacted security@digitalasset.com and followed the [responsible disclosure policy](https://digitalasset.com/security/).
+
+I confirm that this is not a question or a request for technical support by the community, for which the [Daml forum](https://discuss.daml.com/) is available.
+-->
+
+### Describe the error message
+
+<!--
+Enter here the error message, where it occurs
+-->
+
+### To reproduce
+
+<!--
+Add here the steps to reproduce the error message...
+1. start such and such service '...'
+2. write the following code
+3. see error
+-->
+
+### What do you think is bad about the error message?
+
+<!--
+- Is it simply wrong, in that it refers to the wrong code?
+- Is it incomplete, in that it refers to only part of the problem?
+- Is it confusing, in that it refers to complex features?
+- Does it show compiler internals, or parts of the pipeline that you don't know about?
+- Is it insufficient, because it doesn't provide advice?
+-->
+
+### What do you think could be done to improve the error message?
+
+<!--
+- If the error is simply wrong, should it be fixed?
+- Should it provide better context on what caused the error?
+- Does it obscure compiler internals and better explain the source of the error?
+- Should it provide better advice on how to fix the error?
+-->