Wrong error message on ambiguous variable names

[NightRa]

findInNameSpaces: findInNameSpaces

• Throws "Variable not in scope." when it should be "multiple matching variables in scope.", because of the use of catchesM.

Reproduction:
> hermit examples/Mean/mean.hs

set-pp-type Omit
rhs-of 'mean
lam-body
{ application-of 'sum ; let-intro 's }
{ application-of 'length; let-intro 'l }
innermost let-float
reorder-lets ['s, 'l]
let-tuple 'sl
case-expr ; abstract 'xs
app-fun ; let-intro 'sumlength
let-bind ; nonrec-to-rec
binding-of 'sumlength ; remember sumlen
def-rhs ; lam-body ; case-split-inline 'xs