We've addressed the all the issues raised by kos & zcoop98 that were caused by updates in [Stop guessing/auto-detecting a language when you KNOW it will be incorrect](https://meta.stackexchange.com/a/403488/209031)

1. We now exclude tags that aren't part of our predefined list of known good tags from highlighting in both preview and when rendered. This is somewhat tricky because we have two different MD -> HTML engines, one running in client-side running in JS, one in server-side running in C#.
2. We shored up the aliases used for each language block client and server side so they're the same.

### Test Case 1 - Non Existent language tag

**Input**

````
```lang-nonexistant
var x = "123";
```
````

**Output**

```lang-nonexistant
var x = "123";
```


### Test Case 2 - Supported Language Aliases

**Input**

````
```lang-js
var x = "123";
```

```lang-javascript
var x = "123";
```

```lang-console
grep "pattern" filename.txt
```

```lang-shell
grep "pattern" filename.txt
```
````

**Output**

```lang-js
var x = "123";
```

```lang-javascript
var x = "123";
```

```shell
#!/bin/bash
```

```console
#!/bin/bash
```

Thanks for reporting!