Two non-parametric procs in a single file cause errors when running DSLX tests

**Describe the bug**

Having two non-parametric procs in one DSLX file triggers errors when running DSLX tests using the `xls_dslx_test` rule.
The test itself is not even necessary, as it seems that the problem occurs before running the actual test. The error is not triggered when the other proc is parametric.

**To Reproduce**

One can use the following DSLX code to trigger the error:
```rust
import std;

proc Passthrough {
data_r: chan in;
data_s: chan out;

init {()}

config(data_r: chan in, data_s: chan out) {
(data_r, data_s)
}

next(tok: token, state: ()) {
let (tok, data) = recv(tok, data_r);
let tok = send(tok, data_s, data);
}
}

// proc MyOtherProc { // adding a fake parameter removes the error
proc MyOtherProc {
data_r: chan in;
data_s: chan out;

init {()}

config(data_r: chan in, data_s: chan out) {
(data_r, data_s)
}

next(tok: token, state: ()) {
let (tok, data) = recv(tok, data_r);
let tok = send(tok, data_s, data);
}
}
```

The problem may be related to IR translation, as adding the `compare = none` flag to `dslx_test_args` removes the error.
Here are the build rules needed to trigger the problem:

``` python
xls_dslx_library(
name = "passthrough_dslx",
srcs = [
"passthrough.x",
],
)

xls_dslx_test(
name = "passthrough_dslx_test",
dslx_test_args = {
#"compare": "none", # uncommenting this line removes errors
},
library = ":passthrough_dslx"
)
```

The error message is as follows:
```
$ bazel run //xls/examples:passthrough_dslx_test
Executing tests from //xls/examples:passthrough_dslx_test
-----------------------------------------------------------------------------
E0517 09:02:38.735197 2067348 command_line_utils.cc:45] Could not extract a textual position from error message: INTERNAL: Proc ID "MyOtherProc:0" was not found in arg mapping.: INVALID_ARGUMENT: Provided status is not in recognized error form: INTERNAL: Proc ID "MyOtherProc:0" was not found in arg mapping.
```

I pushed the code of this example to [here](https://github.com/antmicro/xls/tree/proc-error). To trigger the error, use:
```
bazel run //xls/examples:passthrough_dslx_test
```

**Expected behavior**

The error should not be triggered.
Also, an `INTERNAL` error is triggered when handling the original error, which should not happen.