db: fix db.Initialize() sqlite3 error checking, add errortype linter

.custom-gcl.yml

@@ -4,3 +4,7 @@ plugins:
   # partitiontest plugin from local source
   - module: 'github.com/algorand/go-algorand/cmd/partitiontest_linter'
     path: ./cmd/partitiontest_linter
+  # errortype plugin for error handling consistency
+  - module: fillmore-labs.com/errortype
+    import: fillmore-labs.com/errortype/gclplugin
+    version: v0.0.7

.golangci-warnings.yml

@@ -6,13 +6,24 @@ linters:
   enable:
     - gosec
     - partitiontest
+    - errortype
   settings:
     gosec:
       excludes: [G101, G103, G104, G107, G112, G114, G115, G202, G204, G301, G302, G303, G304, G306, G307, G404]
     custom:
       partitiontest:
         type: "module"
         description: This custom linter ensures test functions call 'partitiontest.PartitionTest(t)'
+      errortype:
+        type: module
+        description: "errortype helps prevent subtle bugs in error handling."
+        original-url: "https://fillmore-labs.com/errortype"
+        settings:
+          style-check: false
+          deep-is-check: true
+          check-is: true
+          unchecked-assert: false
+          check-unused: true
   exclusions:
     generated: lax
     rules:

ledger/ledgercore/error.go

@@ -27,6 +27,17 @@ import (
 // ErrNoSpace indicates insufficient space for transaction in block
 var ErrNoSpace = errors.New("block does not have space for transaction")
 
+// Verify each custom error type implements the error interface, and declare which are pointer/value receivers.
+var (
+	_ error = (*TxnNotWellFormedError)(nil)
+	_ error = (*TransactionInLedgerError)(nil)
+	_ error = (*LeaseInLedgerError)(nil)
+	_ error = BlockInLedgerError{}
+	_ error = ErrNoEntry{}
+	_ error = ErrNonSequentialBlockEval{}
+	_ error = (*TxGroupMalformedError)(nil)
+)
+
 // TxnNotWellFormedError indicates a transaction was not well-formed when evaluated by the BlockEvaluator
 //
 //msgp:ignore TxnNotWellFormedError
@@ -44,7 +55,7 @@ type TransactionInLedgerError struct {
 }
 
 // Error satisfies builtin interface `error`
-func (tile TransactionInLedgerError) Error() string {
+func (tile *TransactionInLedgerError) Error() string {
 	return fmt.Sprintf("transaction already in ledger: %v", tile.Txid)
 }
 

util/db/initialize.go

@@ -38,7 +38,7 @@ func Initialize(accessor Accessor, migrations []Migration) error {
 		return InitializeWithContext(ctx, tx, migrations)
 	})
 
-	var sqlError *sqlite3.Error
+	var sqlError sqlite3.Error
 	if errors.As(err, &sqlError) {
 		return fmt.Errorf("%w.  Sql error - Code: %d, Extended Code: %d", err, sqlError.Code, sqlError.ExtendedCode)
 	}