Miscellaneous Meta.partially_inline! fixes

I'm not a big fan of this pass, or the way it's written. At a minimum, I'd expect
both better test coverage (when we write similar passes for the core Compiler, we
get away with weak test coverage by relying on user code) and a re-factor to make
this switch exhaustive (it should error if unexpected IR elements are encountered,
instead of just performing an incorrect transformation)

This doesn't make progress on those issues for now, but it at least fixes up a
couple of conspicuous problems I noticed when reviewing #56787

Author: topolarity

base/meta.jl

@@ -362,6 +362,19 @@ function _partially_inline!(@nospecialize(x), slot_replacements::Vector{Any},
         x.edges .+= slot_offset
         return x
     end
+    if isa(x, Core.UpsilonNode)
+        if !isdefined(x, :val)
+            return x
+        end
+        return Core.UpsilonNode(
+            _partially_inline!(x.val, slot_replacements, type_signature, static_param_values,
+                               slot_offset, statement_offset, boundscheck),
+        )
+    end
+    if isa(x, Core.PhiCNode)
+        _partially_inline!(x.values, slot_replacements, type_signature, static_param_values,
+                           slot_offset, statement_offset, boundscheck)
+    end
     if isa(x, Core.ReturnNode)
        # Unreachable doesn't have val defined
        if !isdefined(x, :val)
@@ -381,6 +394,9 @@ function _partially_inline!(@nospecialize(x), slot_replacements::Vector{Any},
         )
     end
     if isa(x, Core.EnterNode)
+        if x.catch_dest == 0
+            return x
+        end
         return Core.EnterNode(x, x.catch_dest + statement_offset)
     end
     if isa(x, Expr)