Code review comment: Shall we add tests to cover the missing lines

Code under review:
private BLangBlockStmt rewriteNestedOnFail(BLangOnFailClause onFailClause, BLangFail fail) {
        BLangOnFailClause currentOnFail = this.onFailClause;
        BLangBlockStmt onFailBody = blockStmtByFailNode.get(fail);
        if (onFailBody == null) {
            onFailBody = ASTBuilderUtil.createBlockStmt(onFailClause.pos);
            onFailBody.stmts.addAll(onFailClause.body.stmts);
            onFailBody.scope = onFailClause.body.scope;
            onFailBody.mapSymbol = onFailClause.body.mapSymbol;
            onFailBody.failureBreakMode = onFailClause.body.failureBreakMode;
            onFailBody.isFromFailNode = true;
            VariableDefinitionNode onFailVarDefNode = onFailClause.variableDefinitionNode;

            if (onFailVarDefNode != null) {
                BVarSymbol onFailErrorVariableSymbol =
                        ((BLangSimpleVariableDef) onFailVarDefNode).var.symbol;
                BLangSimpleVariable errorVar = ASTBuilderUtil.createVariable(onFailErrorVariableSymbol.pos,
                        onFailErrorVariableSymbol.name.value, onFailErrorVariableSymbol.type, rewrite(fail.expr, env),
                        onFailErrorVariableSymbol);
                BLangSimpleVariableDef errorVarDef = ASTBuilderUtil.createVariableDef(onFailClause.pos, errorVar);
                onFailBody.scope.define(onFailErrorVariableSymbol.name, onFailErrorVariableSymbol);
                onFailBody.stmts.add(0, errorVarDef);
            }

            int currentOnFailIndex = this.enclosingOnFailClause.indexOf(this.onFailClause);
            int enclosingOnFailIndex = currentOnFailIndex <= 0 ? this.enclosingOnFailClause.size() - 1
                    : (currentOnFailIndex - 1);
            this.onFailClause = this.enclosingOnFailClause.get(enclosingOnFailIndex);
            onFailBody = rewrite(onFailBody, env);
            BLangFail failToEndBlock = new BLangFail();
            if (onFailClause.isInternal && fail.exprStmt != null) {
                if (fail.exprStmt instanceof BLangPanic) {
                    setPanicErrorToTrue(onFailBody, onFailClause);
                } else {
                    onFailBody.stmts.add((BLangStatement) fail.exprStmt);
                }
            }
            if (onFailClause.bodyContainsFail && !onFailClause.isInternal) {
                onFailBody.stmts.add(failToEndBlock);
            }
            this.onFailClause = currentOnFail;
            blockStmtByFailNode.put(fail, onFailBody);
        }
        return onFailBody;
    }

Line commented on: onFailBody.stmts.add((BLangStatement) fail.exprStmt);

Revised code:
private BLangBlockStmt rewriteNestedOnFail(BLangOnFailClause onFailClause, BLangFail fail) {
        BLangOnFailClause currentOnFail = this.onFailClause;
        
        
        BLangBlockStmt onFailBody = blockStmtByFailNode.get(fail);
        if (onFailBody == null) {
            onFailBody = ASTBuilderUtil.createBlockStmt(onFailClause.pos);
            onFailBody.stmts.addAll(onFailClause.body.stmts);
            onFailBody.scope = onFailClause.body.scope;
            onFailBody.mapSymbol = onFailClause.body.mapSymbol;
            onFailBody.failureBreakMode = onFailClause.body.failureBreakMode;
            onFailBody.isFromFailNode = true;
            VariableDefinitionNode onFailVarDefNode = onFailClause.variableDefinitionNode;

            if (onFailVarDefNode != null) {
                BVarSymbol onFailErrorVariableSymbol =
                        ((BLangSimpleVariableDef) onFailVarDefNode).var.symbol;
                BLangSimpleVariable errorVar = ASTBuilderUtil.createVariable(onFailErrorVariableSymbol.pos,
                        onFailErrorVariableSymbol.name.value, onFailErrorVariableSymbol.type, rewrite(fail.expr, env),
                        onFailErrorVariableSymbol);
                BLangSimpleVariableDef errorVarDef = ASTBuilderUtil.createVariableDef(onFailClause.pos, errorVar);
                onFailBody.scope.define(onFailErrorVariableSymbol.name, onFailErrorVariableSymbol);
                onFailBody.stmts.add(0, errorVarDef);
            }

            int currentOnFailIndex = this.enclosingOnFailClause.indexOf(this.onFailClause);
            int enclosingOnFailIndex = currentOnFailIndex <= 0 ? (this.enclosingOnFailClause.size() - 1)
                    : (currentOnFailIndex - 1);
            this.onFailClause = this.enclosingOnFailClause.get(enclosingOnFailIndex);
            onFailBody = rewrite(onFailBody, env);
            BLangFail failToEndBlock = new BLangFail();
            if (onFailClause.isInternal && fail.exprStmt != null) {
                if (fail.exprStmt.getKind() == NodeKind.PANIC) {
                    setPanicErrorToTrue(onFailBody, onFailClause);
                } else {
                    onFailBody.stmts.add((BLangStatement) fail.exprStmt);
                }
            }
            if (onFailClause.bodyContainsFail && !onFailClause.isInternal) {
                onFailBody.stmts.add(failToEndBlock);
            }
            this.onFailClause = currentOnFail;
            blockStmtByFailNode.put(fail, onFailBody);
        }
        return onFailBody;
    }