Enforce exhaustive enum switches at compile time: remove `default:` from exhaustive type-to-string switches

[adsharma]

Motivation

LogicalOperatorUtils::logicalOperatorTypeToString() threw Unknown logical operator type. at runtime on LSQB q9: the recent COUNT_ANTI_EDGE_CHAIN operator was added to the enum but a case was never added to the type-to-string switch.

-Wall -Wextra (which includes -Wswitch) would have caught this at compile time — but the switch ended in default: throw RuntimeException(...), and any default: label silences -Wswitch. The failure mode was converted from a build error into a runtime crash.

The same bug class exists in the sibling enum→string switches listed below. This was fixed for logicalOperatorTypeToString (see commit adding COUNT_ANTI_EDGE_CHAIN); this issue tracks applying the pattern to the rest.

The pattern

For switches that are exhaustive in intent (every enumerator returns / is handled):

// Before: -Wswitch silently disabled
switch (type) {
case Foo::A: return "A";
default: throw RuntimeException("Unknown type.");
}

// After: -Wswitch enforces coverage; missing enumerator = build failure with -Werror
switch (type) {
case Foo::A: return "A";
}
// No default label: -Wswitch then enforces that every enumerator is handled above.
throw RuntimeException("Unknown type.");  // guards only out-of-range values

Switches using default: UNREACHABLE_CODE; get the same treatment (replace the default label with the unreachable check after the switch).

Candidate files

Exhaustive-in-intent enum→string switches currently carrying a default: label:

• src/common/enums/accumulate_type.cpp (1)
• src/common/enums/conflict_action.cpp (1)
• src/common/enums/drop_type.cpp (1)
• src/common/enums/extend_direction_util.cpp (1)
• src/common/enums/path_semantic.cpp (1)
• src/common/enums/query_rel_type.cpp (2)
• src/common/enums/rel_direction.cpp (2)
• src/common/enums/rel_multiplicity.cpp (1)
• src/common/enums/scan_source_type.cpp (1)
• src/common/enums/table_type.cpp (1)
• src/common/enums/transaction_action.cpp (1)
• src/common/expression_type.cpp (2)
• src/catalog/catalog_entry/catalog_entry_type.cpp (2)
• src/processor/operator/physical_operator.cpp (1)
• src/transaction/transaction_manager.cpp (1 — review; may be semantically non-exhaustive)

Out of scope

Not every switch with a default: should change:

• Switches where default is semantically meaningful, e.g. LogicalOperatorUtils::isUpdate() returns false for everything else. -Wswitch forcing a case per new operator there would be noise.
• Deserialize switches that intentionally tolerate unknown serialized values for forward compatibility.

Verification

With the pattern applied, temporarily commenting out any single case must produce warning: enumeration value 'X' not handled in switch [-Wswitch] — a hard failure under ENABLE_WERROR=ON (CI), and a visible warning in all other configs.

Notes

An X-macro generating both the enum and its string table would guarantee sync by construction, but is less readable/navigable; compiler enforcement via -Wswitch is preferred unless this class of bug recurs.