Rollup merge of #88411 - Aaron1011:remove-session-if-let, r=estebank

Remove `Session.if_let_suggestions`

We can instead if either the LHS or RHS types contain
`TyKind::Error`. In addition to covering the case where
we would have previously updated `if_let_suggestions`, this might
also prevent redundant errors in other cases as well.

src/test/ui/suggestions/if-let-typo.rs

@@ -10,4 +10,5 @@ fn main() {
     if Some(3) = foo {} //~ ERROR mismatched types
     //~^ ERROR destructuring assignments are unstable
     //~^^ ERROR invalid left-hand side of assignment
+    if x = 5 {}  //~ ERROR cannot find value `x` in this scope
 }

src/test/ui/suggestions/if-let-typo.stderr

@@ -9,6 +9,17 @@ help: you might have meant to use pattern matching
 LL |     if let Some(x) = foo {}
    |        +++
 
+error[E0425]: cannot find value `x` in this scope
+  --> $DIR/if-let-typo.rs:13:8
+   |
+LL |     if x = 5 {}
+   |        ^ not found in this scope
+   |
+help: you might have meant to use pattern matching
+   |
+LL |     if let x = 5 {}
+   |        +++
+
 error[E0658]: destructuring assignments are unstable
   --> $DIR/if-let-typo.rs:4:16
    |
@@ -79,7 +90,7 @@ error[E0308]: mismatched types
 LL |     if Some(3) = foo {}
    |        ^^^^^^^^^^^^^ expected `bool`, found `()`
 
-error: aborting due to 9 previous errors
+error: aborting due to 10 previous errors
 
 Some errors have detailed explanations: E0070, E0308, E0425, E0658.
 For more information about an error, try `rustc --explain E0070`.