fix: guard persistBankOp/persistBook against a null session; rename promptText to promptBankName

src/shell/panel/panel_bank_ops.cpp

@@ -95,7 +95,7 @@ std::vector<const Bank*> namedBanks() {
 void doCreateBank() {
     if (!book()) return;
     std::string name;
-    if (!promptText("ReaSampler: create bank", "Bank name:", "", name)) return;
+    if (!promptBankName("ReaSampler: create bank", "Bank name:", "", name)) return;
     const std::string id = bankOpCreate(name);
     if (id.empty()) {
         ShowMessageBox("A bank with that name already exists.",
@@ -115,7 +115,7 @@ void doRenameBank(const std::string& bankId) {
     if (!bk || bk->isPool()) return;
     const std::string current = bk->displayName;  // copy before any mutation
     std::string newName;
-    if (!promptText("ReaSampler: rename bank", "New name:", current, newName)) return;
+    if (!promptBankName("ReaSampler: rename bank", "New name:", current, newName)) return;
     if (!bankOpRename(bankId, newName)) {
         ShowMessageBox("Another bank already uses that name.",
                        "ReaSampler: rename bank", 0);
@@ -417,9 +417,13 @@ namespace {
 // (the change stays valid for the session and persists on the user's next save).
 // Deliberately NO Save-As prompt; do not "align" with persistViewState's prompt
 // idiom. Returns whether a persist actually happened, so persistBankOp can discard
-// its undo block when nothing was written. Session pointer is live for the whole
-// extension lifetime (bankPanelInit at load, before any action registers).
-bool persistBook() { return panel::g_panel.session->saveToActiveProject(); }
+// its undo block when nothing was written. Guards a null session pointer (false,
+// no-op) — see persistBankOp's guard below for why this is defensive rather than
+// dead code.
+bool persistBook() {
+    if (!panel::g_panel.session) return false;  // no live session: nothing to persist
+    return panel::g_panel.session->saveToActiveProject();
+}
 
 // Mints a fresh, genuine REAPER GUID string as a stable bank id (the B2/model
 // design: ids are caller-supplied and stable; the model stays pure and mints none).
@@ -438,8 +442,8 @@ std::string mintBankId() {
 // COMMA GUARD: GetUserInputs splits returned values on a separator defaulting to ',',
 // so the return separator is overridden to \x1f (un-typeable) via the documented
 // `separator=X` trailing pseudo-caption (SDK ~3806) — any printable name round-trips.
-bool promptText(const char* title, const char* caption, const std::string& initial,
-                std::string& out) {
+bool promptBankName(const char* title, const char* caption, const std::string& initial,
+                    std::string& out) {
     std::vector<char> buf(512, '\0');
     // Pre-fill: GetUserInputs seeds the field from the retvals buffer's initial value.
     std::snprintf(buf.data(), buf.size(), "%s", initial.c_str());
@@ -472,7 +476,14 @@ bool promptText(const char* title, const char* caption, const std::string& initi
 // change stands and persists on the user's next save; it just earns no undo point until
 // there is a project to persist into (undo of an unsaved bank op has nothing to roll
 // back to anyway). The Begin/End must still be balanced, hence the close-either-way.
+//
+// NULL-SESSION GUARD: this is a public API (panel_bank_ops.h) with callers outside
+// this TU (e.g. panel_drag.cpp), not all of which are guaranteed to have re-checked
+// the session pointer immediately beforehand. Bail out BEFORE Undo_BeginBlock2 — no
+// block is opened, so there is nothing to balance and no risk of an unbalanced
+// Begin/End pair.
 void persistBankOp(const char* label, bool bumpGeneration) {
+    if (!panel::g_panel.session) return;  // no live session: no-op, no undo point opened
     Undo_BeginBlock2(nullptr);
     // S9: bump the bank-generation counter INSIDE the block, before persistBook(), so the
     // fresh generation rides the same ext-state write the persist makes (persistBook() ->