(from user, didn't check it myself)

indenting region with c-i when text contains tab
Here is the console output I get when running c-i on text containing tab

$>org.erlide.runtime.backend.exceptions.BackendException: {'EXIT',{badarith,[{erlide_text,get_tab_n_spaces,2},{erlide_text,get_tab_spaces,2},{erlide_text,detab,4},{erlide_indent,indent_line,6},{erlide_indent,do_indent_lines,6},{rpc,'-handle_call/3-fun-0-',5}]}} <- erlide_indent:indent_lines('-record(emm_page, {substate, % Substate callback, % CallbackModule imsi, % Imsi, stmsi, % Stmsi, oldstmsi, % oldStmsi talist, % talist paging_tref, % pagingtimer Ref paging_resend, % paging resend count % {stimsi_resends,old_stimsi_resends} paging_timer, % paging timer transport_list, % TransportRefList controldata_gtp % gtp controldata }). ','415','36','0','[{'<<',2}, {after_arrow,4}, {after_binary_op,4}, {after_unary_op,4}, {arrow_nl,0}, {before_arrow,2}, {before_binary_op,4}, {case,4}, {catch,4}, {clause,4}, {comma_nl,0}, {dot_nl,0}, {end_paren,0}, {fun,3}, {fun_body,5}, {function_parameters,2}, {paren,1}, {semicolon_nl,0}, {try,4}]',) @ Runtime<otp_vob/af35588_erlide (/vobs/otp/otp_delivery/suse_x86) R12B []>
at org.erlide.runtime.backend.Backend.rpcx(Backend.java:238)
at org.erlide.runtime.backend.Backend.rpcx(Backend.java:208)
at erlang.ErlideIndent.indentLines(ErlideIndent.java:57)
at org.erlide.ui.actions.IndentAction.callErlang(IndentAction.java:46)
at org.erlide.ui.actions.ErlangTextEditorAction.run(ErlangTextEditorAction.java:147)
at org.eclipse.jface.action.Action.runWithEvent(Action.java:498)
at org.eclipse.ui.commands.ActionHandler.execute(ActionHandler.java:185) at org.eclipse.ui.internal.handlers.LegacyHandlerWrapper.execute(LegacyHandlerWrapper.java:109)
at org.eclipse.core.commands.Command.executeWithChecks(Command.java:475) at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:429)
at org.eclipse.ui.internal.handlers.HandlerService.executeCommand(HandlerService.java:165)
at org.eclipse.ui.internal.keys.WorkbenchKeyboard.executeCommand(WorkbenchKeyboard.java:470)
at org.eclipse.ui.internal.keys.WorkbenchKeyboard.press(WorkbenchKeyboard.java:821)
at org.eclipse.ui.internal.keys.WorkbenchKeyboard.processKeyEvent(WorkbenchKeyboard.java:879)
at org.eclipse.ui.internal.keys.WorkbenchKeyboard.filterKeySequenceBindings(WorkbenchKeyboard.java:568)
at org.eclipse.ui.internal.keys.WorkbenchKeyboard.access$3(WorkbenchKeyboard.java:510)
at org.eclipse.ui.internal.keys.WorkbenchKeyboard$KeyDownFilter.handleEvent(WorkbenchKeyboard.java:126)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
at org.eclipse.swt.widgets.Display.filterEvent(Display.java:1423)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1100)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1125)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1110)
at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:1137)
at org.eclipse.swt.widgets.Widget.gtk_key_press_event(Widget.java:663)
at org.eclipse.swt.widgets.Control.gtk_key_press_event(Control.java:2533)
at org.eclipse.swt.widgets.Composite.gtk_key_press_event(Composite.java:679)
at org.eclipse.swt.widgets.Widget.windowProc(Widget.java:1486)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4234)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:3973)
at org.eclipse.swt.internal.gtk.OS._gtk_main_do_event(Native Method)
at org.eclipse.swt.internal.gtk.OS.gtk_main_do_event(OS.java:5593)
at org.eclipse.swt.widgets.Display.eventProc(Display.java:1192)
at org.eclipse.swt.internal.gtk.OS._g_main_context_iteration(Native Method)
at org.eclipse.swt.internal.gtk.OS.g_main_context_iteration(OS.java:1487)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2969)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2389)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2353)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2219)
at org.eclipse.ui.internal.Workbench$4.run(Workbench.java:466)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:289)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:461)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at com.windriver.ide.application.CopyOfIDEApplication.start(CopyOfIDEApplication.java:104)
at com.windriver.ide.application.UnifiedSWTSwingApplication.access$101(UnifiedSWTSwingApplication.java:42)
at com.windriver.ide.application.UnifiedSWTSwingApplication.start(UnifiedSWTSwingApplication.java:56)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:169)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:106)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:76)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:363)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:176)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:508)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:447)
at org.eclipse.equinox.launcher.Main.run(Main.java:1173)
at org.eclipse.equinox.launcher.Main.main(Main.java:1148)